The present invention relates to a method of treatment of a radioactive liquid waste including high-level liquid waste and medium- or low-level liquid waste produced from a reprocessing plant, to decompose sodium compounds contained in the liquid waste for the recovery and reuse of sodium and for the volume reduction of the radioactive liquid waste to be disposed, thus facilitating the vitrification or bitumen solidification of the liquid waste.
High-level liquid waste produced from a reprocessing plant essentially comprises a large amount of sodium nitrate and a small amount of fission products. This type of liquid waste is generally vitrified by melting it together with a large amount of a glass forming agent.
On the other hand, medium- or low-level liquid waste substantially comprises sodium nitrate and a slight amount of fission products. This type of liquid waste is generally mixed with bitumen under heating and the mixture is solidified and discarded.
In order to obtain a vitrified product having excellent properties, the sodium content in the product must be below a specified limit. Therefore, in order to convert a large amount of high-level liquid waste into a vitrified product having excellent properties, a large amount of a glass forming agent must be used, which disadvantageously brings about an increase in the amount of waste.
Further, in the treatment of medium- or low-level liquid waste, the mixing of sodium nitrate with bitumen under heating involves risk of fire or explosion. Thus much attention is required and the working efficiency is poor.